Why do we suffer?
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Reply: The impression of suffering is meant for your awakening to truth and the ending of separation.
Mistaking the rope for the snake triggers fears that are founded on the falsehood of the mind.
Separation is a false impression that triggers resistance as well as seeking which is unhappy. Thus unhappiness leads you to inquire into the freedom that defies the mind. 
In time you realize the emptiness of suffering and the emptiness of the sufferer. You awaken to the vastness of Being and you dissolve as that.